275 lines
8.5 KiB
C
275 lines
8.5 KiB
C
/*
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* Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
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* Written by Alex Tomas <alex@clusterfs.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public Licens
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
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*/
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#ifndef _EXT4_EXTENTS
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#define _EXT4_EXTENTS
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#include "ext4.h"
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/*
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* With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks
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* becomes very small, so index split, in-depth growing and
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* other hard changes happen much more often.
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* This is for debug purposes only.
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*/
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#define AGGRESSIVE_TEST_
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/*
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* With EXTENTS_STATS defined, the number of blocks and extents
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* are collected in the truncate path. They'll be shown at
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* umount time.
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*/
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#define EXTENTS_STATS__
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/*
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* If CHECK_BINSEARCH is defined, then the results of the binary search
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* will also be checked by linear search.
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*/
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#define CHECK_BINSEARCH__
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/*
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* If EXT_STATS is defined then stats numbers are collected.
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* These number will be displayed at umount time.
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*/
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#define EXT_STATS_
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/*
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* ext4_inode has i_block array (60 bytes total).
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* The first 12 bytes store ext4_extent_header;
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* the remainder stores an array of ext4_extent.
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* For non-inode extent blocks, ext4_extent_tail
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* follows the array.
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*/
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/*
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* This is the extent tail on-disk structure.
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* All other extent structures are 12 bytes long. It turns out that
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* block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
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* covers all valid ext4 block sizes. Therefore, this tail structure can be
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* crammed into the end of the block without having to rebalance the tree.
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*/
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struct ext4_extent_tail {
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__le32 et_checksum; /* crc32c(uuid+inum+extent_block) */
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};
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/*
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* This is the extent on-disk structure.
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* It's used at the bottom of the tree.
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*/
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struct ext4_extent {
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__le32 ee_block; /* first logical block extent covers */
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__le16 ee_len; /* number of blocks covered by extent */
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__le16 ee_start_hi; /* high 16 bits of physical block */
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__le32 ee_start_lo; /* low 32 bits of physical block */
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};
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/*
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* This is index on-disk structure.
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* It's used at all the levels except the bottom.
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*/
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struct ext4_extent_idx {
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__le32 ei_block; /* index covers logical blocks from 'block' */
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__le32 ei_leaf_lo; /* pointer to the physical block of the next *
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* level. leaf or next index could be there */
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__le16 ei_leaf_hi; /* high 16 bits of physical block */
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__u16 ei_unused;
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};
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/*
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* Each block (leaves and indexes), even inode-stored has header.
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*/
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struct ext4_extent_header {
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__le16 eh_magic; /* probably will support different formats */
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__le16 eh_entries; /* number of valid entries */
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__le16 eh_max; /* capacity of store in entries */
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__le16 eh_depth; /* has tree real underlying blocks? */
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__le32 eh_generation; /* generation of the tree */
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};
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#define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
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#define EXT4_EXTENT_TAIL_OFFSET(hdr) \
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(sizeof(struct ext4_extent_header) + \
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(sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))
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static inline struct ext4_extent_tail *
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find_ext4_extent_tail(struct ext4_extent_header *eh)
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{
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return (struct ext4_extent_tail *)(((void *)eh) +
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EXT4_EXTENT_TAIL_OFFSET(eh));
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}
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/*
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* Array of ext4_ext_path contains path to some extent.
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* Creation/lookup routines use it for traversal/splitting/etc.
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* Truncate uses it to simulate recursive walking.
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*/
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struct ext4_ext_path {
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ext4_fsblk_t p_block;
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__u16 p_depth;
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struct ext4_extent *p_ext;
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struct ext4_extent_idx *p_idx;
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struct ext4_extent_header *p_hdr;
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struct buffer_head *p_bh;
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};
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/*
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* structure for external API
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*/
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/*
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* Maximum number of logical blocks in a file; ext4_extent's ee_block is
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* __le32.
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*/
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#define EXT_MAX_BLOCKS 0xffffffff
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/*
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* EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
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* initialized extent. This is 2^15 and not (2^16 - 1), since we use the
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* MSB of ee_len field in the extent datastructure to signify if this
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* particular extent is an initialized extent or an uninitialized (i.e.
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* preallocated).
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* EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
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* uninitialized extent.
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* If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
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* uninitialized one. In other words, if MSB of ee_len is set, it is an
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* uninitialized extent with only one special scenario when ee_len = 0x8000.
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* In this case we can not have an uninitialized extent of zero length and
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* thus we make it as a special case of initialized extent with 0x8000 length.
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* This way we get better extent-to-group alignment for initialized extents.
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* Hence, the maximum number of blocks we can have in an *initialized*
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* extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
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*/
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#define EXT_INIT_MAX_LEN (1UL << 15)
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#define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
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#define EXT_FIRST_EXTENT(__hdr__) \
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((struct ext4_extent *) (((char *) (__hdr__)) + \
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sizeof(struct ext4_extent_header)))
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#define EXT_FIRST_INDEX(__hdr__) \
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((struct ext4_extent_idx *) (((char *) (__hdr__)) + \
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sizeof(struct ext4_extent_header)))
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#define EXT_HAS_FREE_INDEX(__path__) \
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(le16_to_cpu((__path__)->p_hdr->eh_entries) \
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< le16_to_cpu((__path__)->p_hdr->eh_max))
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#define EXT_LAST_EXTENT(__hdr__) \
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(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
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#define EXT_LAST_INDEX(__hdr__) \
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(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
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#define EXT_MAX_EXTENT(__hdr__) \
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(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
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#define EXT_MAX_INDEX(__hdr__) \
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(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
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static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
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{
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return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
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}
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static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
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{
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return (struct ext4_extent_header *) bh->b_data;
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}
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static inline unsigned short ext_depth(struct inode *inode)
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{
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return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
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}
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static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
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{
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/* We can not have an uninitialized extent of zero length! */
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BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
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ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
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}
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static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
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{
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/* Extent with ee_len of 0x8000 is treated as an initialized extent */
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return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
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}
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static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
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{
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return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
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le16_to_cpu(ext->ee_len) :
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(le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
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}
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static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
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{
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ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
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}
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/*
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* ext4_ext_pblock:
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* combine low and high parts of physical block number into ext4_fsblk_t
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*/
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static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
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{
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ext4_fsblk_t block;
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block = le32_to_cpu(ex->ee_start_lo);
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block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
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return block;
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}
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/*
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* ext4_idx_pblock:
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* combine low and high parts of a leaf physical block number into ext4_fsblk_t
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*/
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static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
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{
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ext4_fsblk_t block;
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block = le32_to_cpu(ix->ei_leaf_lo);
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block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
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return block;
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}
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/*
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* ext4_ext_store_pblock:
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* stores a large physical block number into an extent struct,
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* breaking it into parts
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*/
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static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
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ext4_fsblk_t pb)
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{
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ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
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ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
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0xffff);
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}
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/*
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* ext4_idx_store_pblock:
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* stores a large physical block number into an index struct,
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* breaking it into parts
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*/
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static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
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ext4_fsblk_t pb)
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{
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ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
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ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
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0xffff);
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}
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#endif /* _EXT4_EXTENTS */
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